Mold Nobody Spilled

Wednesday, October 28th, 2026 — The attic hatch stuck, and when it opened the air that came down was warm and smelled like wet cardboard. The sheathing along the north slope was dark in a fan shape that started at a flexible duct and spread toward the ridge. The duct was the bath fan from the hall bathroom. It ended in the attic, taped to nothing, blowing shower air at the underside of the roof. There was no stain on the ceiling below. There was no claim for a storm, a pipe, or a backup. The homeowner had gone up to store luggage, seen the black, and called it in as mold.

Most of the mold files in this series start with water that escaped from somewhere on a date someone can name. This one does not. The colony is real. The moisture that fed it is real. What is missing is a covered cause of loss, and that absence is the claim. Adjusters who go looking for a pipe they can hang the file on will either invent one or pay a maintenance problem. The inspection is a walk from the top of the house to the bottom, looking for where the house makes its own water.

The attic

Go up before you talk coverage. Take a moisture meter, a light, and a mask. You are looking for a pattern, not a species.

A bath fan, a dryer, or a kitchen hood that terminates in the attic, or that terminates against a soffit so the damp air is pulled straight back in, leaves a plume of discoloration on the sheathing and on the nearest rafters. The wood is wettest at the end of the duct and drier as you move away. In cold weather the same plume may be frost on the nails in the morning and a drip by noon. That is condensation. Warm moist air hit a cold surface, dropped its water, and kept doing it every time someone showered. Nobody's supply line failed.

Write the path in the file. Where the duct starts, where it ends, whether it is kinked, disconnected, or was never connected. Photograph the termination and the plume in the same frame so a reviewer can see they touch. Note the bathroom below. A fan that runs and dumps into the attic was installed wrong, or the duct fell off years ago and was left there. It did not fail on the day of the report.

Two other attic patterns look similar and are not this loss. Staining that follows a roof penetration, a boot, a valley, or a chimney, and that lines up with weather, is a roof leak until you prove otherwise. Staining that follows the eaves in a band, worse after a winter, may be an ice dam. Those can be covered causes of loss. A plume centered on a bath duct is not. Do not call all three "attic mold" in the same sentence. The cause is the coverage.

While you are up there, look at the ventilation and the insulation. Blocked soffit vents, insulation packed into the eaves, and a bath duct buried in loose fill are the usual companions. They explain the condensation. They are also maintenance and construction conditions, not a peril.

The crawlspace

The hatch at the other end of the house often tells the same story from below. Joists and subfloor with a fuzzy growth on the underside, heaviest toward the middle of the house or toward a dirt section with no plastic, and no plumbing stain running from a fitting. The soil is damp. The plastic, if anyone ever put it down, is torn or stops short of the walls. Foundation vents are painted shut or buried in flower beds.

Ground moisture rises into a cool crawlspace all summer. It condenses on the joists, the colony follows, and the insulation hangs there holding the damp against the wood. This can go on for years. The homeowner notices it when a contractor replacing a furnace takes a picture, or when a musty smell reaches a closet. There is still no date of loss. There is a condition.

Meter the wood. If the joists are dry on the day you visit and the growth looks old, say so. A dry colony is not evidence that a pipe broke last week. Look anyway for a supply line, a drain, a condensate line, and a water heater pan, because a crawlspace can hold both problems and the covered one is easy to miss once you have decided the file is a humidity problem. A wet fitting with fresh staining is a plumbing discharge. Photograph it separately from the general growth on the joists. The two findings can produce two different coverage answers in the same hole.

The mechanical closet and the windows

Cold supply ducts running through a hot, humid space sweat. The water beads on the outside of an uninsulated or torn-wrapped duct, drips onto the ceiling below, and leaves a stain that looks exactly like a supply-line leak. The difference is on the duct. The insulation is missing or the vapor wrap is open, the stain is under a supply run rather than under a joint in the copper, and the dripping happens in August when the air conditioner has been on, not on the day a fitting let go. Wipe a bead off the metal and watch it return while the system runs. That is surface condensation, not a discharge from inside the system.

A condensate pan that overflows is the other file, and it should not be mixed into this one. Water that escapes from the drain pan or the condensate line because the line clogged is a sudden discharge from an appliance. Water that forms on the outside of a cold duct is not. If you find both, scope them apart. The pan overflow can be covered. The sweating duct is the condition that was there all summer.

Windows do a smaller version of the same thing. A tight house with no ventilation, single-pane glass, and someone drying clothes indoors will run water down the sash every cold morning. The sill swells, the trim spots, and the homeowner reports mold in every bedroom. Open the window track. If the growth is on the lower sash and the sill, and the wall cavity above the window is dry, you are looking at condensation on the glass, repeated all winter, from how the house is lived in and from glass and ventilation that were never up to the climate.

Why the form does not respond

A standard homeowners policy pays for damage from a covered cause of loss. On an HO-3 the dwelling is open-peril, which means the damage is covered unless an exclusion applies, and then the fungi coverage gives a limited amount back only when the fungi result from a covered cause. Condensation, a fan vented into an attic, and a crawlspace with no vapor barrier fail that test in more than one place.

• No covered cause. The water was not a sudden discharge from plumbing, heating, or air conditioning. It was moisture the house produced by being lived in and built the way it was built. Without a covered cause, the fungi give-back never opens.

• Wear, deterioration, and maintenance. The form excludes wear and tear, deterioration, and wet or dry rot in the company of the other maintenance exclusions. Sheathing that has been taking shower vapor for years, and joists that have been taking ground moisture for years, are in that family. Name the mechanism in the letter. Do not substitute the word "maintenance" for a description.

• Faulty workmanship. A bath fan that was ducted into the attic, or never ducted at all, is how the house was built or altered. Faulty, inadequate, or defective design and workmanship are excluded. The exclusion often has an ensuing-loss sentence. Read it. Ensuing loss helps when a covered peril follows the bad work, a fire starting in a defective fixture, for example. It does not turn the condensation itself into a covered peril. The colony is the result of the excluded condition, not a new peril that arrived later.

The fungi exclusion is the last sentence, not the first. If you deny only because "mold is not covered," you have skipped the reason the mold is there, and you have written a letter that is wrong on the next file, the one where a pipe did break. Lead with the cause. Then say the fungi coverage does not apply because it requires a covered cause of loss.

The exceptions, so you do not deny the wrong attic

Three attic findings should stop a condensation denial.

An ice dam. Meltwater that backs up under shingles along the eaves, soaks the decking in a band above the heated wall, and shows up inside on the ceiling at the exterior wall, is a pattern adjusters on a standard HO-3 are used to covering, because the water entered as a result of the ice, not as flood or surface water. Confirm the water exclusion on the form in your hand before you say so. The exclusion is not the same on every carrier's paper. If the ice dam is the cause, the wet insulation and the colonized drywall that followed it can be covered, and the fungi limit applies to the colonized portion the way it does on any other covered water loss.

A storm opening. Missing shingles, a lifted flashing, or a tree strike that let rain onto the deck is a covered opening if wind or falling objects is covered. The rain that followed is not "condensation." Scope the opening, the water, and any growth separately, and do not let a bath-fan plume elsewhere in the same attic turn the storm damage into a maintenance denial.

A covered repair that created a new path. A roofer or a mitigation contractor, in the middle of a loss you are already paying, disconnects a duct, leaves the deck open overnight, or blocks the only soffit vent with stored insulation. The water or the condensation that follows that act may be part of the open claim, or it may be the contractor's workmanship, which is a different recovery. It is not the homeowner's ten-year bath-fan problem. Photograph what the contractor changed and put the date on it.

The letter that tells them what to fix

The homeowner still has a black attic. The denial has to be specific enough to be fair and useful enough that they know what has to change in the house. The letter is not a promise to pay for that work.

We inspected the attic on April 3. The hall bath fan discharges into the attic through a flexible duct that ends against the north roof deck. The discoloration on the sheathing is centered on that opening and decreases as you move away from it. We did not find a roof opening, an ice-dam pattern, or a plumbing leak. The policy covers sudden, accidental damage from a covered cause of loss. It does not cover condensation from a fan vented into the attic, or the mold that grew because that moisture has been hitting the sheathing. Our payment on this claim is zero. Venting the fan to the exterior and drying the sheathing are the repairs that address what we found. Those repairs are not covered by this policy.

Change the facts to match the crawlspace or the duct if that is the file. Keep the structure. What you saw, what you did not see, which exclusion or missing peril applies, what would fix it, and that the fix is not covered. A letter that says only "mold coverage is excluded" leaves the homeowner free to report the same attic again after the next humid week, and leaves you with nothing to point to when they do.

Offer to look again if they later find a fitting, a flashing, or a stain that was not visible on this visit. That sentence costs nothing. It also keeps a real plumbing leak from being swept into a denial you wrote about a fan.